1. Technical Field
The present invention relates to a method for forming a barbed suture in the surgical field. The method of the invention allows producing a high quantity of barbed suture in a reduced time and in a very cost-effective way. The invention also relates to the barbed suture obtained by this method.
2. Background of Related Art
Surgical knots have been used for ages in order to anchor and allow a conventional suture, in other words a smooth suture without barbs, to perform its role in tissue reapproximation for example. Anyway, surgical knots reduce the tensile strength of conventional sutures by thinning and stretching the material forming the suture. Indeed, it is known that the weakest portion of any suture line is the knot.
Moreover, the tying of surgical knots introduces the potential of human error. A knot-secured conventional suture may create an uneven distribution of tension across the wound, with the higher tension burden placed at the knots. In addition, in minimally invasive laparoscopic surgery, the ability to quickly and properly tie surgical knots presents a challenge. The skill necessary for performing intra- or extracorporeal knot tying for laparoscopic surgery may be acquired only with practice and patience, yet surgeons need to master such a skill in order to properly perform closure procedures. Laparoscopic knot tying is also more mentally and physically stressful on surgeons.
Given the excessive relative wound tension on the knot and the reasonable concerns of surgeons for suture failure due to knot slippage, there is a natural tendency toward overcoming these potential issues by over-tightening knots. However, tighter knots may be worse for wound healing and strength than looser knots. Surgical knots, when tied too tightly, can cause localized hypoxia, reduced fibroblast proliferation, and excessive tissue overlap, leading to reduced strength in the healed wound.
Eventually, a surgical knot yields the highest density of foreign body material in any given suture line and the volume of a knot may be directly related to the total amount of surrounding inflammatory reaction. If minimizing the inflammatory reaction in a wound is important for optimized wound healing, then minimizing knots sizes or even eliminating knots altogether would be beneficial as long as the wound-holding strength of the suture line is not compromised.
For all these reasons, the use of barbed suture, suture with barbs, has tremendously increased in the past years. In particular, one of the most costly parts of a surgical procedure is time in the operating room. With rising healthcare costs, efficiency in the operating room is becoming more of a priority. Significantly faster closure times have been observed with the use of knotless barbed sutures. The use of knotless barbed suture can securely reapproximate tissues with less time, cost, and risks.
Barbed sutures are known. They basically consist in strands of smooth suture provided with barbs on their surfaces. Barbed sutures are generally made of the same materials as conventional sutures and offer several advantages for closing wounds compared with conventional sutures. A barbed suture includes an elongated body that has one or more spaced barbs, that project from the surface of the suture body along the body length.
The barbs are generally arranged to allow passage of the barbed suture in one direction through tissue but resist movement of the barbed suture in the opposite direction (one-way suture). One advantage of barbed sutures is the provision of a non-slip property. Barbed sutures are known for use in cosmetic, laparoscopic and endoscopic procedures. The number of barbs needed for a particular suture may be influenced by the size of the wound and the strength required to hold the wound closed. Like a conventional suture, a barbed suture may be inserted into tissue using a surgical needle.
In some circumstances, a random configuration of barbs on the exterior surface of the suture is preferred to achieve optimal holding of the wound closure for a particular wound. However, in other circumstances, where the wound or tissue repair needed is relatively small, a reduced number of barbs may be desired.
Various methods of forming barbs on sutures have been proposed such as mechanical cutting, laser cutting, injection molding, stamping, extrusion and the like. However, such methods may be difficult or costly, in particular when a specific arrangement or configuration of barbs is needed for an appropriate surgical procedure.
For example, conventional cutting methods of forming barbs may involve cutting with a blade into the elongate body of the suture, where the elongate body may be a monofilament for example. Barbed sutures may be fabricated from monofilament fibers by a micro-machining technique, which escarpes barbs into the fiber around the circumference in a variety of configurations. Cutting methods have therefore significant drawbacks as they weaken the core of the suture and narrow its functional diameter. Moreover, they are costly and have slow manufacturing cycle time.
Accordingly, there is a continuous need for methods of forming barbs on a suture that are less difficult to implement, more efficient and cost effective. There is also a continuous need for methods allowing varying the size, the location and the depth of the barbs, as well as the amount of barbs present on the suture, depending on the contemplated surgical application.